Abstract:
Both oil and environmental hypoxia are known to constrain the maximum metabolic rate. This dataset describes the degree to which hypoxia and oil exposure are additive stresses on the oxygen supply cascade. This dataset comprises of metabolic rate data assessed in individuals across a variety of ambient oxygen levels, with oil exposure as a second manipulated factor.
Suggested Citation:
Ackerly, Kerri and Andrew Esbaugh. 2020. Additive effects of oil exposure and hypoxia on aerobic scope in red drum (Sciaenops ocellatus). Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-qje8-1n86
Data Parameters and Units:
The first tab in this file (Fish & Trial Information) shows the fish identification, mass (grams), total length (cm), standard length (cm), chamber ratio, chamber volume (mL), oil or control exposure condition, MMR recovery DO (% air saturation), oil exposure date, MMR trial date, SMR trial start date, SMR trial end date, the water temperature at the start of the trial, salinity at the start of the trial, the temperature at the end of the trial, and salinity at the end of the trial.
The mass is the overall wet mass of the fish. Total length is the length of the fish from the tip of the snout to the tip of the tail fin. Standard length is the length of the fish from the tip of the snout to the base of the caudal fin. Chamber ratio is the ratio of the mass of the fish to the volume of the respirometry chamber. The chamber volume is the amount of water that the respirometry chamber contained. Oil or control exposure is whether the fish was exposed to a 20% HEWAF (oil) or clean seawater (control) for 24h before the start of the exercise trial. Oil exposure date is the day the oil or control exposure started. MMR trial date is the date the fish underwent chase and MMR measure. SMR trial start date is the day the SMR trial started. SMR end date is the date the SMR trial ended. Temperature start is the temperature in degrees Celsius at the beginning of the trial. Salinity start is the salinity at the start of the trial in parts per thousand (ppt). Temperature end is the temperature in degrees Celsius at the end of the trial. Salinity end is the salinity at the end of the trial in parts per thousand (ppt).
The tabs following are the raw data for each individual mentioned in the Fish & Trial Information tab. The tab is labelled with the appropriate fish’s ID. The tab contains information regarding the date the trial took place, whether the fish was oil or control, the date the respirometry trials (MMR and SMR) started, the recovery level in % air sat the fish was placed in after MMR, and the chamber # the fish was placed in. The file also contains the loop, the details of the loop (in seconds), the MO2 of that chamber, the R2 of the chamber, the amount of background there is calculated for each loop, the MO2 minus the background, the phase of the trail, and the average DO in % air sat for each loop.
A loop is a single respirometry measure period. The next column is the details of the loop. It contains a certain number of seconds the chamber the fish is to flush with seawater (flush period), the number of seconds the chamber recirculates the water without measuring oxygen consumption by the fish (wait period), and the number of seconds the chamber recirculates water and measures oxygen consumption of the fish. Loop times vary with phase. Background loop times have an extended measure time. Pcrit measures have only measure phases. Pcrit phase is the end of the SMR trial where water only recirculates and measures. The MO2 of the chamber is the metabolic rate of the fish, which is calculated by how much oxygen they consume during the measure phase. The R2 is the statistical measure of how well your data fit a line (a decline in the amount of oxygen in the chamber). The R2 must be above 0.95 to be included in the dataset. The background of the chamber is a measure of the amount of bacterial respiration that occurs in the chamber when the fish is not present. These phases have longer measure periods. The background is then calculated incrementally increasing with each loop. The background – MO2 column is the MO2 value for that loop minus the calculated background for that loop. The phase of the trial includes background start (the measure of bacterial respiration before the fish were in the chambers), MMR (maximum metabolic rate, the first 5 measures after exercise that the fish was in the chamber), EPOC (excess post-exercise oxygen consumption, the recovery time following exercise while the fish returns to baseline), SMR (standard metabolic rate, the 24h measure period of SMR), PCRIT (critical oxygen threshold, the period following SMR when the chamber was closed to new water), and background end (the measure of bacterial respiration after the fish were in the chambers). The averaged DO (dissolved oxygen) is the amount of oxygen (as % air sat) measured across the entire loop.
Please note that the individuals in the control group had no oil exposure, individuals in the oil group were all exposed to oil, individuals exposed to oil were exposed to 29.04 μgL-1 ΣPAH50 (20% HEWAF), and NA means data are not available.
Methods:
Dataset contains data on farm-raised red drum exposed to either a 20% HEWAF of OFS oil or clean seawater. 64 individuals were placed into 5 L of exposure for 24 h. After exposure, control and oil exposures were placed into an experimental respirometry chamber under normoxia or hypoxia following maximum exercise challenges. Individuals had their aerobic scope and hypoxia tolerance measured. Juvenile red drum were kept in holding tanks and acclimated for a minimum of 2 weeks before being used in this study.
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